OpenWrt
lorenetworkingIT support
The replacement Linux firmware for consumer and small-business network devices, which began after a router vendor's use of Linux obliged them to publish their source under the kernel's licence.
It is the cleanest real-world demonstration of copyleft working as designed: a company shipped Linux in a product, the licence required the changes back, and a community turned that release into a full independent firmware that now supports hundreds of devices. The practical value today is longevity - OpenWrt keeps devices patched years after their manufacturer has stopped caring, which is the embedded industry's central failure and, so far, its only broadly available answer.
Also known as: router firmware, linksys wrt54g, dd-wrt